Method for the refining of gasolines to high-octane fuel

ABSTRACT

A method of refining gasoline stock in order to obtain highoctane fuels which comprises mixing the gasoline stock with complex compounds of the lower-valency transition metals selected from the group consisting of lower-valency transition metal carbonyls, the complex compounds of slats of said metals with ntype ligands, and the complex compounds of salts of said metals with strong reducing agents, followed by heating the reaction mixture in the 80* to 100*C temperature range and distilling off the target product.

United States Patent [1 1 Nametkin et al.

1451 Feb. 11, 1975 METHOD FOR THE REFINING OF GASOLINES TO HIGH-OCTANE FUEL [76] Inventors: Nikolai Sergeevich Nametkin,

Leninsky prospekt l3, kv. l1; Sergei Pavlovich Gubin, B.Pochtovaya ulitsa, 40, kv. Vladimir Dmitrievich Tjurin, Leninsky prospekt, 67, kv. 33; Viktor Viktorovich Fedorov, 3 Samotechny pereulok, 24, kv. 88; Valery Zeilikovich Usachev, ulitsa Zarechnaya, l1, korpus 1, kv. 4, all of Moscow; Mikhail Semenovich Matveev, ulitsa Shkolnaya 3, kv. l2, Gorkovskaya oblast; Leonid Ivanovich Larionov, ulitsa Minina 15-A, kv. 8, Gorky; Alexandr Solomonovich Eliner, ulitsa Shvernika, 9, korpus 4, kv. 34; Ruslan Yakolevich Barashkov, Bebozhny pereulok, l9, korpus l7, kv. 4, both of Moscow, all of U.S.S.R.

[22] Filed: Dec. 29, 1972 [21] Appl. No.: 319,383

[] Foreign Application Priority Data Dec. 30, 1971 U.S.S.R 1728801 [52] US. Cl 208/243, 208/244, 208/295,

[51] Int. Cl. C10g 29/00 [58] Field of Search 208/243, 244, 257, 295, 208/249, 189

[5 6] References Cited UNITED STATES PATENTS 809,087 1/1906 Blackmore 208/244 1,558,631 10/1925 2,247,148 6/1941 2,306,933 12/1942 2,615,831 10/1952 Bishop et al. 208/244 FOREIGN PATENTS OR APPLICATIONS 1,483,583 6/1967 France 208/244 Primary ExaminerDelbert E. Gantz Assistant Examiner.luanita M. Nelson Attorney, Agent, or Firm-Holman & Stern [57] ABSTRACT A method of refining gasoline stock in order to obtain high-octane fuels which comprises mixing the gasoline stock with complex compounds of the lower-valency transition metals selected from the group consisting of lower-valency transition metal carbonyls, the complex compounds of slats of said metals with n-type ligands, and the complex compounds of salts of said metals with strong reducing agents, followed by heating the reaction mixture in the to C temperature range and distilling off the target product.

4 Claims, No Drawings METHOD FOR THE REFINING 01F GASOLTNES TO HIGH-OCTANE FUEL This invention relates to method of refining gasolines into high-octane fuel and, more specifically, to methods of improving the antiknock rating of gasolines and for purifying gasolines sulphur compounds and dienes which favour gum formation.

The gasolines produced by thermal cracking or thermal catalytic cracking processes and also the gasolines obtained as by-products of low-octane gasoline steamcracking process, after being purified of their dienes and sulphur compounds, find widespread use as motor fuel components or catalytic reforming feedstock.

Exhaustive or selective hydrofining processes are extensively employed in treating the aforementioned gasolines. Selective hydrofining comprises treating said gasolines with hydrogen over heterogeneous catalysts under strictly specified conditions which results in saturating about 90% of the dienes present and about of the oxidation resistant olefins, however the octane rating of the thus-refined gasolines remains low.

In order to increase the octane rating, antiknock additives are introduced into said gasolines, and among the available antiknock additives lead-free organometallic compounds may be mentioned such as, for example, cyclopentadienyl derivatives of manganese, iron and other transition metals. This method of improving the gasoline octane number is, however, disadvanta' geous in that it necessitates the use of antiknock additives prepared from expensive raw materials.

An essential requirement for commercial gasolines is their low sulphur compounds content, however conventional hydrofining techniques make it possible to effect only a partial removal of sulphur compounds.

A process for refining industrial hydrocarbon mixtures, such as gasolines, diesel oils, fuel oils, lubricating oils, and the like is known wherein the removal of mercaptan sulphur contained in said products, eg in gasolines, is effected by a treatment with oxygen, oxygencontaining gases, or with agents which yield oxygen, and with the process of refining being conducted in the presence of a catalyst, viz., an organometallic compound of the type Me,|(R) (CO),,, in which Me represents a metal selected from the group consisting of metals from Groups VIA, VIIA and VIII of the periodic system, a is an integer from 1 to 4 inclusive, R may be an aromatic or cyclopentadienyl ligand, x is an integer of from 1 to 5 inclusive, and y is an integer of from O to 9 inclusive.

Suitable metals are manganese, iron, cobalt, nickel, molybdenum and chromium.

Examples of suitable aromatic ligands are benzene and its alkylated or arylated homologues, such as toluene, xylenes, mesitylene, hexamethylbenzene, ethylbenzene, diethylbenzenes, propylbenzene, diphenyl, diphenylmethane, triphenylmethane, tetraphenylmethane, diphenylethane, tetrahydronaphthalene, anthracene, phenanthrene, pyrene, benzpyrene and coronene, and also cyclopentadiene or its alkylated or arylated homologues, such as ethylcyclopentadiene, diethylcyclopentadiene, phenylcyclopentadiene and fluorene.

The process of refining is carried out at a tempera ture of from 50 to 140C for a short period of time and in the presence ofa catalyst taken in an amount of from 0.01% to 0.1% by weight, and with superatmospheric pressure being resorted to in some instances. This treatment yields gasolines which contain relatively harmless disulphides, while the dienes and reactive olefins undergo polymerization and condensation, with the resulting products being high boiling-point liquids or precipitates. In most cases, the organometallic catalysts are decomposed under the effect of heat or light, as well as when the raw materials being refined are acted upon by large amounts of oxygen under elevated temperatures, so that the precipitates formed also contain, apart from the converted impurities, the decomposed organometallic catalysts, which are expensive materials.

When gasolines are refined by the present method, in order to remove the mercaptan sulphur contained therein and the organometallic catalysts used which also possess antiknock properties, said organometallic compounds need not be removed at all or removed completely from the refined gasolines. These refined gasolines may be after-treated, which step necessitates additional expenditures.

Hence, the known refining process is disadvantageous in that it makes use of individual organometallic compounds as catalysts, i.e. of expensive materials prepared from pure starting products. Another disadvantage of the known process is that the mercaptans contained in the gasolines being refined are converted into relatively inert disulphides, but the total content of sulphur in the gasolines is not diminished.

Moreover, refining the cracked gasolines by the known process causes the dienes contained in said gasolines to undergo polymerization under the effects of oxygen and which forms slimy precipitates, thereby rendering the recovery of said dienes impracticable.

It will be noted that all the prior art processes for refining gasolines in order to obtain high-octane fuels suffer from a common drawback, viz., the necessity of resorting to a process flow sheet comprising a plurality of steps, such as the removal of dienes, purification of the sulphur compounds, and preparation and introduction of antiknock additives, wherein each of the aforesaid steps necessitates the use of specialized process equipment, andwhich calls for specific process conditions, etc.

No single-stage process has heretofore been developed for carrying out said refining of gasolines.

It is therefore an object of the: present invention to provide a method for refining gasolines for the purpose of obtaining high-octane fuels wherein said process makes it possible to carry out the purification of said gasolines of both the sulphur compounds and the dienes in a single step and to simultaneously improve the antiknock rating of said gasolines.

In accordance with this and other objects, the method of the invention comprises mixing gasolines with complex compounds of the lower valency transi tion metals, viz., carbonyls of transition metals, the complex compounds of salts of said metals with n-type ligands, and the complex compounds of salts of said metals with strong reducing agents, followed by heating the resulting mixture in the to C range and subsequently distilling off the target product.

The aforesaid treatment results in the formation of high boiling-point compounds and precipitates which contain the products of the reaction between said complex compounds of lower-valency transition metals with the sulphur compounds and dienes contained in the charge stock. Said high boiling-point compounds and precipitates, upon distilling off the target gasolines, remains behind as still bottoms which exert practically no contamination effect on the commercial product. Refining the gasolines by the present method involves the formation of pi-complexes as a result of the reaction between the dienes contained in the gasolines being processed and the lower-valency transition metal compounds, said pi-complexes being an effective antiknock additive.

The present method is superior to the known method in many aspects, particularly in that it avoids the necessity of preparing individual organometallic compounds, which are expensive, but also provides for the possibility of preparing highly efficient pi-complexes directly in the gasoline being refined due to the presence of dienes in said gasoline.

The preferred transition metal carbonyls are iron, nickel and molybdenum carbonyls or a mixture of manganese and iron carbonyls. The nickel carbonyltriphenylphosphine complex is the preferred complex of the transition metal compounds with the n-type 1igands, while it is preferable to use the manganese chloride-triphenylphosphine-lithium aluminium hydride complex as the complex compound of the transition metal salts with strong reducing agents.

In order to intensify the process, i.e. to enhance its rate and completeness, it is expedient to treat the gasolines with said lower-valency transition metal complexes under UV-irradiation conditions.

The present invention provides markedly improved economical effect, in as much as the method of gasoline refining to obtain high-octain fuels involves one stage only and utilizes relatively inexpensive reagents. It is noteworthy that in the refining method, according to the present invention, the dienes contained in the charge stock are not wasted, and can be recovered as a result of decomposing the separated pi-complexes and further utilized in the petrochemical industry.

The gasolines refined by the method of the invention display essentially higher quality characteristics, viz., the total sulphur content is half as great as that of the gasoline stock, and the octane numbers are increased, on the average, over by 20 units (from 60-70 to 8592 as determined by the motor-method test), and the commercial quality of the refined gasolines (odour, colour, stability, and gum-forming tendency) being likewise substantially improved.

The present method is practised as follows.

The gasoline stock and complex compounds of a lower-valency transition metals are placed in a flask fitted with a reflux condenser. Where ultra violet irradiation is required, the flask is made of quartz and an UV radiation source is placed for example at a distance of cm. from the flask. The reaction mixture is heated at a temperature of from 80 to 100C for several hours, generally for a period of from 2 to hours, and followed by distilling off the refined gasoline by conventional procedures. The target product is a clear colourless or slightly yellow liquid which is stable when exposed to the effects of air for a prolonged period of time. this being indicative of the absence of oxidationscnsitive dienes. The octane numbers are determined by the motor-method test.

For a better understanding of the present invention, the following examples are given for illustration.

EXAMPLE 1 1 litre of an unstable gasoline from a thermal cracking process (an octane rating 65.5; mercaptan. content. 0.06% by weight) and 2 g. of nickel carbonyl are heated for a period of 6 hours, followed by distilling oft the gasoline fraction whose boiling point is under 200C and which has an octane rating of 83.0. The doctor test is negative.

EXAMPLE 2 Example 3.

0.5 litre of gasoline obtained from the catalytic cracking process (octane rating, 76.2; total sulphur content, 0.26% by weight) and 2 g. of iron nonacarbonyl are heated for a period of 18 hours, while irradiating the reaction mixture with UV light. Distillation yields a gasoline fraction boiling under 195C which has an octane rating of 92. The total sulphur content is 0.12% by weight.

EXAMPLE 4.

0.5 litre of unstable gasoline obtained from the thermal cracking process (octane rating, 64; content of mercaptans, 0.074% by weight) and 5 ml. of iron pentacarbonyl are heated for a period of 10 hours, while irradiating the reaction mixture with UV light. Distillation yields a gasoline fraction boiling under 200C which has an octane rating of 82. The doctor test is negative.

EXAMPLE 5.

0.5 litre of by-product gasoline from the hydrocarbon gas pyrolysis process(steam cracking to ethylene) and 2 g. of iron dodecarbonyl are heated for a period of 2 hours, followed by distilling off a gasoline fraction that boils under C and which has an octane rating of 96.

EXAMPLE 6.

0.5 litre of an unstable gasoline from the thermal cracking process (octane rating, 65.5; total sulphur content, 0.56% by weight; mercaptan sulphur content, 0.025% by weight) and 2.5 ml. of iron pentacarbonyl are heated for a period of 2 hours, and followed by distilling off the gasoline fraction boiling under C, and which has an octane rating of 78, shows a negative doctor test, and is characterized by a total sulphur content of 0.28% by weight.

EXAMPLE 7.

0.5 litre of an unstable gasoline from a thermal cracking process (octane rating, 60) and 2 g. of a mixture consisting of manganese and iron dodecacarbonyls taken in a weight ratio of 1:3 are heated for a period of 6 hours. Subsequent distillation separates the 195C boiling fraction having an octane rating of 82.5.

EXAMPLE 8.

EXAMPLE 9.

0.5 litre of an unstable gasoline obtained from the thermal cracking process (octane rating, 68.5; mercaptan sulphur content, 0.048% by weight), 1 g. of cobalt carbonyl and l g. of triphenylphosphine are heated for a period of 10 hours. Distillation of the reaction mixture yields a gasoline fraction boiling under 200C and which has an octane rating of 84. The doctor test is negative.

EXAMPLE 10.

0.5 litre of an unstable gasoline obtained from the thermal cracking process (octane rating, 62.3; content of mercaptan sulphur, 0.042% by weight), 1 g. of mangenese chloride, 1 g. of triphenylphosphine, and 2 g. of lithium aluminium hydride are heated for a period of 10 hours, followed by distilling off the gasoline fraction boiling under 195C and having an octane rating of 80. The doctor test is negative.

What is claimed is:

l. A method of refining gasoline to obtain highoctane fuels comprising mixing the gasoline stock with complex compounds of lower-valency transition metals selected from the group consisting of iron, nickel, molybdenum and manganese, said complex compounds selected from the group consisting of the carbonyls of said metals, the complex compounds of the salts of said metals with triphenylphosphine ligands, and the complex compounds of the salts of said metals with lithium aluminum hydride, followed by heating the resulting mixture in the to C temperature range and dis tilling off the target product.

2. A method as claimed in claim 1 wherein the lowervalency transition metal carbonyls are selected from the group consisting of iron, nickel and molybdenum carbonyls or a mixture of iron and manganese carbon yls.

3. A method as claimed in claim 1 wherein the complex compound of the lower-valency transition metal salt with triphenylphosphine is a cobalt carbonyltriphenylphosphine complex.

4. A method as claimed in claim 1 wherein the complex compound of a lower-valency transition metal salt with lithium aluminum hydride is a manganese chloride-triphenylphosphine-lithium aluminium hydride complex. 

1. A METHOD OF REFINING GASOLINE TO OBTAIN HIGH-OCTANE FUELS COMPRISING MIXING THE GASOLINE STOCK WITH COMPLEX COMPOUNDS OF LOWER-VALENCY TRANSITION METALS SELECTED FROM THE GROUP CONSISTING OF IRON, NICKEL, MOLYBDENUM MANGANESE, SAID COMPLEX COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF THE CARBONYLS OF SAID METALS, THE COMPLEX COMPOUNDS OF THE SALTS OF SAID METALS WITH TRIPHENYLPHOSPHINE LIGANDS, AND THE COMPLEX COMPOUNDS OF THE SALTS OF SAID METALS WITH LITHIUM ALUMINUM HYDRIDE, FOLLOWED BY HEATING THE RESULTING MIXTURE IN THE 80* TO 100*C TEMPERATURE RANGE AND DISTILLING OFF THE TARGET PRODUCT.
 2. A method as claimed in claim 1 wherein the lower-valency transition metal carbonyls are selected from the group consisting of iron, nickel and molybdenum carbonyls or a mixture of iron and manganese carbonyls.
 3. A method as claimed in claim 1 wherein the complex compound of the lower-valency transition metal salt with triphenylphosphine is a cobalt carbonyl-triphenylphosphine complex.
 4. A method as claimed in claim 1 wherein the complex compound of a lower-valency transition metal salt with lithium aluminum hydride is a manganese chloride-triphenylphosphine-lithium aluminium hydride complex. 